1. Field of the Invention
This invention relates generally to sound reproduction systems. More particularly, this invention relates to transmission media such as cables used for the transference of audio signals from sound generation sources such as compact disc, digital video disk players, microphones, and acoustic pickups or transducers on musical instruments to amplifiers and speaker for sound reproduction. Even more particularly, this invention relates to the transfer of audio signals by way of fiber optic cables.
2. Description of Related Art
Audio/Visual systems such as home entertainment systems or sound reproduction systems for theaters and auditoriums must transfer audio and/or video signals from sound and video generation equipment to speakers or video displays. The most common connector utilized for connecting these audio and video systems, is what is commonly referred to as an “RCA” connector, variations of which are described in U.S. Pat. Nos. 5,564,942 (Lee) and 5,676,565 (Vagnoni). The “RCA” connector consists of a cylindrical member adapted for connection at one end to a cable and having a pin and a contact, or ground, sleeve projecting from the other end. The pin engages in a corresponding socket in a terminal, or jack, to form the “positive” connection. The contact sleeve extends over a cylindrical flange of the jack in an interference fit to form the “negative”, or ground, connection. As a result, current can flow to the audio/visual reproduction devices from the audio/visual generation equipment connected to the other end of a cable connected between two of the “RCA connectors. The “RCA connector” is a common term that is also referred to commonly as “audio jack connectors”, “phone-connectors”, and the like.
Monster Cable Products, Inc., Brisbane, Calif. is a manufacturer of high performance cables that connect audio/video components for home, car and professional use. Many of the cable types manufactured by companies such as Monster Cable Products employ the RCA s attached to specialty cables for the transfer of audio and video signals. However, if the audio and/or video generation devices are at a great distance (>10 m) from the speakers or the video displays, the signal quality is degraded. Electronic noise from induced electronic noise, from ground differentials, and from the electrical characteristics of the cables themselves contributes to the lower quality signal. This limits the distance of that the audio and/or video generation devices are from the speakers and/or the video displays.
Often speakers and video displays actually incorporate amplifiers to overcome any losses and to attempt to recover and eliminate any distortion accumulated in the transmission over large distances. Some entertainment systems even employ fiber optic transmission devices to isolate the generation devices from the reproduction devices. TOSLINK from Toshiba America Electronic Components, Inc, Irvine, Calif. and described in the “Toshiba-Fiber-Optic Devices TOSLINK Product Guide”, Toshiba America Electronic Components, Inc, Irvine, Calif., 2001 is a fiber optical link that is employed in consumer entertainment systems for the transmission of the digitally encoded audio data from a compact disc to a receiver. Toshiba manufactures the transmitters and receivers that are incorporated in consumer equipment such as compact disc players and audio amplifiers.
U.S. Pat. No. 4,282,605 (Bose) describes a vehicle sound system that has a power amplifier integrated with a loudspeaker at each of four remote locations. An LED or diode laser transmits an electrical signal from a tuner or tape player at low level modulated on a corresponding light signal over optical fibers to each remote location to a phototransistor that converts the light signal into a corresponding electrical signal that is amplified by the power amplifier and then reproduced by the loudspeakers. Leads from the vehicle battery carry D.C. power to each location for energizing the power amplifiers and phototransistors.
U.S. Pat. No. 4,715,671 (Miesak) details a fiber-optic signal transmission link that is used in place of electric audio cable to inter-connect performing musicians and all the necessary pieces of music processing equipment being used in a performance. The fiber-optic link isolates all the people involved in the performance from potential electrical and physical hazards created by the electric audio cables being used.
U.S. Pat. No. 4,945,806 (Merrill, Jr.) teaches a fiber optic musical instrument digital interface (MIDI). The digital interface is a converter that transforms electrical MIDI signals from an electronic musical instrument (or electronic musical device) into light signals. These light signals travel down a fiber optic cable to another fiber optic MIDI link where they are converted back into their original electrical form and output to another electronic musical instrument (or electronic musical device).
U.S. Pat. No. 5,483,367 (Han) describes an audio system where recovered audio signals from a receiver or a digital recording device are used to re-modulate secondary carrier signals and are transmitted by a light emitting diode to a headphone. A photosensitive receiver is incorporated in the headphones to recover the audio signal for driving the speakers of the headphones.
U.S. Pat. No. 5,483,371 (Farinelli, Jr.) provides a distribution system for audio and video services from a centralized source using lightwave signals generated from terminal equipment through an optical carrier to multiple locations in a facility. The terminal equipment reversibly converts audio, video, and control signals from electrical into lightwave signals. The terminal equipment also provide for electrical output at the remote locations with the appropriate format for various audio and video speakers and displays. A controller selects and converts audio communication signal into a standard audio format and directs the signal to the desired remote location in response to the control signal.